The former Labour leader tweeted that Chloe Swarbrick has set out a compelling case for improving access to medicinal cannabis.

She also encouraged people to tune in to the first debate on Ms Swarbrick's bill in Parliament next Wednesday.

Ms Clark is now on a global drug policy commission which promotes the reduction of harm from drugs.

The Government's Misuse of Drugs Amendment Bill introduced to Parliament last month will make cannabis products more easily available to patients with a terminal illness or in chronic pain.

An advisory committee will be established to review the current requirements for prescribing medicinal cannabis, and set minimum product quality standards to "improve patient safety and give medical practitioners confidence".

The bill also allows for the domestic cultivation and manufacture of medicinal cannabis products, including oils and balms.

Ms Swarbrick's member's bill is seen as more liberal, allowing anyone with a debilitating condition or terminal illness to use raw cannabis or cannabis products with the support of a doctor.

The first-term Green MP took to Facebook this week to ask for the public's help in getting her bill passed.

Ms Swarbrick said in a video that New Zealand lags far behind other progressive countries in our medicinal cannabis laws.

She said people who use cannabis for pain relief shouldn't be treated like criminals and the bill is a good first step towards legalisation.

MPs will be given a conscience vote on Ms Swarbrick's bill, meaning they don't have to vote along party lines.

The Greens confidence-and-supply agreement with Labour includes a referendum on recreational cannabis.